Phosphine borines and their preparation



United States Patent 3,092,665 ?HGS?HINE BORENES AND THEiRP'EEEPARATi-QN Ross 3. Wagner, Whittier, Califl, assignor to AmericanPotash & Chemical Corporation, a corporation of Delaware No Drawing.Fiied h'iar. 14-, 1969, Ser. No. 14,553

8 (Ilairns. (Cl. 266-6065) This invention relates in general tophosphine borines and more particularly to phosphine borine compoundswhich are derived from various tertiary phosphines and boron tribromide;these phosphine borines may be added to gasoline which may containtetraethyl lead (TEL) and which will probably contain ethylenedichloride and dibromide (in the case of automotive fuels) and ethylenedibromide alone (in the case of aviations fuels), the phosphine borinesserving to reduce preignition of gasoline used as a motor fuel.

It is the object of this invention to provide for preparation of certainhosphine borines which are particularly useful as preignition additivesfor gasoline.

Ancillarly objects and advantages of this invention, if not specificallyset forth, will become apparent in the source of the description whichfollows.

Broadly, this invention concerns phosphine borines of the generalformula R PzBBr where each R is hydrocarbon and where the number ofcarbon atoms in the three R groups totals 4 to 30, inclusive.

These materials may be added to unleaded gasoline or gasoline whichcontains TEL or a similar metal-containing anti-detonant such asmethylcyclopentadienyl manganese tricarbonyl, and serve as excellentpreignition additives therein, as set forth in greater detail in ourco-pending application Serial No. 796,223, filed March 2, 1959.

When the phosphine borines of this invention are added to' motor fuel,the resulting motor fuel is found to have a low preignition index and ahigh resistance to detonation knocking. Another effect of the use ofthese phosphine borines is to decrease the tendency of the presence ofTEL in the gasoline to raise the octane requirement of the engine inwhich the gasoline is used. A further advantage of these phosphineborines as gasoline additives is that such phosphine borines are highlyresistant to hydrolysis, as a result of which they have little tendencyto be leached from the fuel by the action of such free Water as may bepresent. In this respect, the phosphine borines as a class are decidedlyadvantageous as compared with most other boron-containing gasolineadditives which are highly vulnerable to hydrolysis. The phosphineborines of this invention are also superior to the closely relatedcompounds R P:BCl and R P:BF (e.g., (CH P:BCI (CH P:BF with respect tohydrolytic stability. For example, in a series of tests wherein 0.81 mg]atoms P/l concentration in leaded gasoline is stored in the presence ofwater in an iron container for several months (which conditions simulatethe environment commonly found in refineries, shipping and storagefacilities and in automobile gasoline tanks), it was found that thefiuoro derivatives apparently convert to the water soluble dimeric formlce In similar tests, compounds of the type R P:BCl were found to beeven less satisfactory. On standing, precipitates formed containingboron and nitrogen (from the gasoline). Bromo analogs showed noformation of a precipitate or other deleterious affects of the typeencountered with the trifluorides and trichlorides.

A further desirable feature of most of the phosphine bromoborines ofthis invention is that they are liquids or low-melting solids and allare amply soluble in hydrocarbons. The latter property is especiallyimportant in a gasoline additive since additives which have lowsolubilities have a strong tendency to precipitate and form soliddeposits when the fuel mixture is vaporized in the carburetor. It isdesirable, but not essential, that the phosphine bromoborines below-melting materials, since this property also reduces the tendency ofthe additives to precipitate and form the aforementioned solid deposits.Such deposits cause malfunctioning of the engine in addition todefeating the purpose of feeding the additive into the combustionchamber. Liquids are also desirable from a material-handling standpointsince they may be blended conveniently with liquid fuels.

Also, it is selfevident that if the compounds are to be used as gasolineadditives, they must be sufiiciently soluble in the hydrocarbon fuelmaterial to provide the desired results. For example, for a standardleaded gasoline containing 3 ml. per gallon of tetraethyl lead, it isnecessary that the phosphorus-containing additive be present at 0.3theory, which represents 3.07 org-atoms of P per gallon or 0.81 mg-atomsof P per liter. In the table below, the solubility of certain of thecompounds of this invention in petroleum ether is contrasted with thesolubility of various other closely related compounds:

Sol. in Unleaded Gasoline-Type Hydrocar- Compound ,M.P., C. bon) B.R,100 C.)

g./1. mmoles/l.

(CHahCzHrPZBBl'a 155. 5-157. 5 1. 5 4. 4 CH3(C H )2P:BBr -121 3. 2 9.1

(OH3).1P:BBr3. 267-268 0. 0. 54 (O H )3P:BBr;- 118-119 5.1 13.8(n-O3H7)3PZBB1'3 159-161 3. 65 8. 8 (11-0411 3P BBra 200-201 2. 8 6. 2

requirements at low levels since there is essentially no loss byextraction.

Finally, the fact that bromine may here be introduced in the form of thephosphine borine compound permits a reduction in the amount of ethylenedihalide normally required in leaded gasoline; this enables a reductionin costs by providing means for simultaneously controlling ignition andscavenging lead with a single additive.

Such a phosphine bromoborine, when used as a preignition additive forgasoline, combines the known beneficial effects of both boron andphosphorus in a single molecule of relatively small size and lowermolecular weight; but, unexpectedly, small amounts of phosphinebromoborines are found to be superior to mixtures of individualcommercially-available preignition additives containing phosphorus onthe one hand and boron on the other. Further, the phosphine borines arerelatively nonreactive and resist decomposition, even at relatively hightemperatures.

The range of effective concentrations for these materials and details oftheir effects on gasoline will not be further described here as thisinformation is set out in the aforementioned co-pending application.

A general preparative method for these new compounds is as follows: To aweighed quantity of the boron tribromide contained in a suitablereaction vessel in added an equimolar quantity of the tertiary phosphineat such a rate that the evolved heat can be dissipated by external meansand the reaction mixture may be maintained as a liquid. The reverseaddition may be used if more convenient. A large number of tertiaryphosphines are known; see, for example, pages 3137 of OrganophosphorusCompounds, Kosolapotf, John Wiley & Sons, New York, 1950.

Specific examples are set forth below showing the preparation of thematerials of this invention, but these are for illustrative purposesonly and are not to be interpreted as imposing limitations on the scopeof the invention other than as set forth in the appended claims.

Example I Into an evacuated tube cooled to -l96 C. were condensed 2.3 g.(25.5 mmoles) dimethylethylphosphine. followed by 6.5 g. (25.9 rnmoles)boron tribromide. The tube was sealed and warmed to -78 C., whereuponimmediate formation of the adduct dimethylethylphosphine tribromoborine,(CH C H P:BBr occurred. The tube was opened at room temperature and thesolid product was recrystallized from ethyl alcohol to give 7.9 g. (23.2mmoles, 91% yield) of colorless solid melting at 155.5 157.5 C.

Analysis.--Calcd. for C.,H BBr Pz P, 9.09; Br, 70.37; B, 3.18. Found: P,9.01; Br. 70.2; B, 3.15.

Example II In a similar manner, 1.3 g. (0.0125 mmole) ofmethyldiethylphosphine and 10.4 g. (41.5 mmoles) of boron tribromide in30 ml. of hexane yielded 3.4g. (0.0096 mmole, 77.3% yield) of the adductmethyldiethylphosphine tribromoborine, CH (C H P:BBr from methyl alcoholmelting at 120-121 C.

Analysis.-Calcd. for C H BBr P: P, 8.73; Br, 67.59; B, 3.05. Found: P,8.78; Br, 67.50; B, 3.11.

Example 111 To a solution of 15 g. (0.127 mole) of triethylphosphine in150 m1. of hexane cooled to -78 C. by means of a Dry Ice bath was addedslowly, with stirring, 37.7 g. (0.15 mole) of boron tribromide under anatmosphere of argon. The resulting white solid was stirred for 15minutes in the cooling bath and for one hour at room Example IV In asimilar manner, 6 g. (0.0375 mole) of tri-n-propylphosphine and 12 g.(0.047 mole) of boron tribromide in ml. of hexane yielded 13 g. (0.032mole, 84.4%) of white crystals from isopropyl alcohol melting at 159 161C.

Analysis.-Calcd. for C I-I BBr P: P, 7.54; Br, 58.36; B, 2.63. Found: P,7.60; Br, 58.58; B, 2.63.

Example V A nitrogen-swept 250 ml. round-bottom flask was charged with100.73 g. (0.402 mole) of boron tribromide while the flask was held inan ice bath. To the flask was slowly added 81.33 g. tributylphosphine atsuch a rate that the reaction mixture was maintained in a fluid statewithout excessive reflux of the BBr A good yield of the additionproduct, (C H P:BBr M.P. 200201 C., was obtained after recrystallizationfrom either npropyl alcohol, ethyl acetate, or a methanol-ethyl acetatemixture.

Example VI In the fashion of Example III above, phenyldimethylphosphineand boron tribromide were reacted both with and without a solvent. Theyield was 94%; the compound obtained has a M.P. range of 119-121 C.

Example VII In a similar manner, the compound m,p'C2H5C6I I4(CH3 2PBB1};

was prepared in a 72% yield and found to have a melting point range of6890 C. The wide range was due to the fact that the compound was amixture of the mand p-isomers.

Analysis.Calcd. for C H BBr P: P, 7.43; Br, 57.52; B, 2.60. Found: P,7.38; Br, 57.30; B, 2.60.

Example VIII In a similar manner, compound 2,5-(CH C H (CH P:BBr

was prepared in an 86% yield and found to have a melting point range of161-163" C.

Analysis.Calcd. for C H BBr P: P, 7.43; Br, 57.52; B,2.60. Found: P,6.88; Br, 56.86; B, 2.63.

Example IX In a similar fashion, the compound 2,5-(CH3) 2C5H3(Il-C4H9) PBB1];

was prepared in 88% yield and found to have a melting point range of107109 C.

Analysis.Calcd. for C H BBr P: P, 6.18; Br, 47.86; B, 2.16. Found: P,5.99; Br, 47.26; B, 2.21.

Following the method set forth above, various other materials may beprepared in like fashion; e.g., see the table below.

selected from the class consisting of alkyl and cycloalkyl together withan aryl radical; each of said alkyl radicals Phosphine Phosphine BorincProduct CHz(CI-IQ) POH3 BB1; (CH3)CH2(CH2)4PIBBI3 CH (CH P CH3 BBra(CH3) CH2(CH2)5P:BB13

OHflCHmPCHa BBra (CH3) CH2(CH2)aP:BBra

As aforementioned, a test for preignition has been devised and the newcompounds of this invention have been compared with other closelyrelated compounds, as a result of which the superiority of thesecompounds has been made apparent. Briefly, this test involves measuringthe number of instances per unit time of motor operation in which flamesoccur in the combustion chamber prior to the time at which the normalflames produced by the spark occur, in general following the proceduredescribed =by Hirschler, McCullough and Hall, SAE Trans. 62, 40, (1954).Efliciency of the preignition additive can be measured by thepreignition index, which is a percentage of such abnormal flamesoccurring in the additivecontaining test gasoline as compared with thebase fuel, i.e., the same TEL-containing gasoline which has not beentreated with the preignition additive.

Obviously, many modifications and variations of the invention may bemade without departing from the spirit and scope thereof and only suchlimitations should be imposed as are indicated in the appended claims.

This application is a continuation-in-part of application Serial No.796,294, filed March 2, 1959, and now abandoned.

I claim:

1. Compounds of the general formula R PzBBr where R is selected from thegroup consisting of two radicals References Cited in the file of thispatent UNITED STATES PATENTS 2,879,301 Stewart et al Mar. 24, 1959FOREIGN PATENTS 1,035,628 Germany Aug. 7, 1958 OTHER REFERENCES Hewittet al.: J. Chem. Soc. (London), pp. 530-4 Brown: J. Chem. Soc., page1250 (1956) (London).

1. COMPOUNDS OF THE GENERAL FORMULA R3P:BBR3 WHERE R3 IS SELECTED FROMTHE GROUP CONSISTING OF TWO RADICALS SELECTED FROM THE CLASS CONSISTINGOF ALKYL AND CYCLOALKYL TOGETHER WITH AN ARYL RADICAL; EACH OF SAIDALKYL RADICALS HAVING BETWEEN ONE AND TWELVE CARBON ATOMS, THE SAID RGROUPS TOGETHER CONTAINING FROM EIGHT TO THIRTY CARBON ATOMS.